Hi Ben,
Assuming the 150mm f8 Skywatcher is the achromat (doublet objective lens), then here are some user reviews:
http://www.excelsis.com/1.0/entry/sk...2866708e6f8668
If it is the 150mm ED f7 apochromat (triplet objective lens), then review is here:
http://www.opticalvision.co.uk/documents/107.pdf
Given the price quoted and the f ratio, safer to assume they are selling the achromat doublet here.
Hope that helps.
Kind regards,
Bill